RepStrapOko

cvoinescu
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Re: RepStrapOko

Post by cvoinescu » Sun Jul 27, 2014 10:50 am

It won't be out by 0.5 mm. It's going to be only slightly less precise than a part printed with a 0.35 mm nozzle. Say, where the part printed with a 0.35 mm nozzle may be out by 0.05 mm (in the X and Y direction), the one printed with the 0.5 mm nozzle may be out by 0.07 mm. That's not a big deal.

The limitation is in the surface finish, the minimum size of detail that can be printed (including less sharp corners), and the minimum wall thickness. The dimensions in the horizontal plane will be accurate, because the slicer takes the width of the extruded filament into account. In effect, the precision in the horizontal plane is limited by the positioning accuracy of the machine, and by the calibration and uniformity of the extrusion. If anything, printing with a larger nozzle results in smoother extrusion. The Z direction is more problematic: with standard slicers, the Z detail and dimensional accuracy is limited by the layer thickness, so features are of the right dimension only if that's a multiple of the layer thickness.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

WillAdams
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Re: RepStrapOko

Post by WillAdams » Sun Jul 27, 2014 10:47 pm

cvoinescu wrote:The Z direction is more problematic: with standard slicers, the Z detail and dimensional accuracy is limited by the layer thickness, so features are of the right dimension only if that's a multiple of the layer thickness.
Interesting.

Are there any slicing programs which will dynamically adjust the layer thickness to get the right dimension?
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

WillAdams
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Re: RepStrapOko

Post by WillAdams » Wed Jul 30, 2014 3:31 am

Beginning on the calibration:

Image

20mm thin wall ( http://www.thingiverse.com/download:17273 ) --- sliced solid, not sure why the lower portion has gaps.... for the curious, the measurements I got off of it were: extruded filament width ~= 0.016" (0.4064mm) -- 0.0175" (0.4445mm) / 0.5mm thin wall box (sliced solid) --- wall thickness ~= 0.020" (0.508mm) -- 0.030" (0.762mm) --- the latter number seems to be from mis-aligned layers --- need to tighten up the Z-axis carriage.
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

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